計算BMI程序

Question

這是通過輸入的體重和身高來計算BMI

#ifndef BMIVIEWER_H 
#define BMIVIEWER_H 
#include <QWidget> 
#include <QGridLayout> 
#include <QLineEdit> 
#include <QLabel> 
#include <QPushButton> 
#include <QLCDNumber> 
#include <QErrorMessage> 
#include <QString> 
#include <QMessageBox> 

class BmiViewer : public QWidget { 
    Q_OBJECT 

public: 

    BmiViewer(); 
    void calculateBmi(); 

private: 
QLineEdit* heightEntry; 
QLineEdit* weightEntry; 
QLCDNumber* result; 
QErrorMessage* error; 
}; 

#endif // BMIVIEWER_H 

bmiviewer.cpp

#include "bmiviewer.h" 
BmiViewer::BmiViewer(){ 
setWindowTitle("MMI Calculator"); 
QGridLayout* layout = new QGridLayout; 
QLabel* inputWeightRequest = new QLabel ("Enter weight in Kg:"); 
weightEntry = new QLineEdit; 
QLabel* inputHeightRequest = new QLabel ("Enter height in meters:"); 
heightEntry = new QLineEdit; 
QPushButton* calc = new QPushButton ("Calculate"); 
QLabel* labelbmi = new QLabel ("BMI"); 
result = new QLCDNumber; 

result->setSegmentStyle(QLCDNumber::Flat); 
result->setDigitCount(8); 

layout->addWidget (inputWeightRequest, 0,0); 
layout->addWidget (weightEntry, 0,1); 
layout->addWidget (inputHeightRequest, 1,0); 
layout->addWidget (heightEntry, 1,1); 
layout->addWidget (calc, 2,1); 
layout->addWidget (labelbmi, 3,0); 
layout->addWidget (result, 3,1); 

setLayout(layout); 

//connect signals and slots 

connect(calc,SIGNAL(clicked()),this, SLOT(calculateBmi())); 

} 

void BmiViewer::calculateBmi(){ 
int wanswer=0; 
int hanswer=0; 
double bmi; 
QString iStr = weightEntry->text(); 
QString iStrh = heightEntry->text(); 
bool ok; 
wanswer = iStr.toInt(&ok); 
hanswer = iStrh.toInt(&ok); 
if (!ok) { 
error = new QErrorMessage(this); 
error->showMessage("Please enter a valid integer"); 
return; 
} 


    //calculate BMI 

    bmi=wanswer/(hanswer*hanswer); 
    result->display(bmi); 

    } 

的main.cpp

#include <QApplication> 
#include "bmiviewer.h" 

int main(int argc, char *argv[]) { 
    QApplication a(argc, argv); 
    BmiViewer w; 
    w.show(); 

    return a.exec(); 
} 

當我編譯它的程序它輸出：Object :: connect：在bmiviewer.cpp中沒有這樣的插槽BmiViewer :: calculateBmi（）：29

它顯示界面，但沒有計算完成。

Answer 1

添加行

public slots: 

void calculateBmi(); 

您從未聲明過BMI之前起作用的槽，因此它不能連接。